Sunday, February 12, 2012

For most bicycle applications when we talk about torque, it’s as a measurement of how much we tighten a bolt or component. A torque wrench is a wrench that uses a beam scale, clicker or digital scale to tell us when we've reached the intended amount of force, or torque.

Bicycle torque requirements range from 4 Newton-Meters to 50 or more. A single torque wrench will not work for that entire range, but a very basic beam style wrench that will cover the range of all the lower torque fasteners can be bought for around $60.00. A larger wrench for the higher torque fasteners can be bought for around $70.00. Electronic torque wrenches start at around $225.00.

For carbon fiber frames and components in particular, measuring torque and not just trusting to “feel” is critical. For stems, handlebars and seatposts, the difference between a component slipping because it is too loose, and that same component breaking from over-tightening the bolts is a pretty fine line. On carbon handelbars and seatposts in particular, tightening the bolts to the appropriate torque sometimes isn’t enough to keep the bar or seatpost from slipping and an assembly paste for carbon fiber components is required. Otherwise it’s sometimes possible to tighten the bolts until the stem or seatpost is damaged without ever getting the bar or seatpost to hold tight.

One final note: putting grease or oil on the threads of bolts is an important step in assembly. Bolts that aren’t lubricated will have a tendency to bind metal-on-metal and seem to have a higher torque than they actually do.

As always, if you have questions on this subject or other mechanic questions, please stop by the shop and ask one of our mechanics about it.